The invention relates to an implement having a head part, a drive part adjoining the head part in the longitudinal direction, which drive part is associated with an actuating member which is drivable in opposite directions, which actuating member is connected transmission-wise to a toggle lever mechanism via which mechanism a clamping arm of a toggle-lever clamping device (or a welding electrode of a toggle-lever welding arm, or a broach or other mandrel, or an impressing or stamping device) is drivable, for use in automotive body manufacturing in the automotive industry, wherewith the drive part has an electric motor which drives the toggle lever mechanism via a transmission device.
There are many forms of implements in the known art which satisfy the above general description.
Inter alia, so-called toggle-lever clamping devices are known, in which a head part in the form of a force-exerting head (clamping head) is connected to a piston and cylinder unit which has a piston movable in two directions via a pressure medium such as compressed air, wherein the piston plunger extends into the inner space of the force-exerting head (clamping head) which head accommodates a toggle lever mechanism via which mechanism a clamping arm is drivable which can be advanced and retracted around a shaft (swing pin) which is fixed to the housing, whereby, e.g., vehicle body components (sheet metal and the like) can be clamped. As a rule, in this connection such so-called toggle-lever clamping devices also have an opposing jaw member to enable clamping of the vehicle body component(s) between the clamping arm and the opposing jaw member.
Toggle-lever clamping devices of this type are described in, e.g., DE 196 16 441 C1.
EP 1 066 929 A2 discloses a toggle-lever clamping device wherein the drive part comprises an electric motor.
Also known is the use of toggle lever mechanisms for “clinch” apparatuses whereby sheet metal parts which are to be joined are subjected to very high local pressure and are deformed to the extent of incipient flow, resulting in a bond analogous to spot welding.
Toggle-lever clamping devices are also known in the form of impressing or stamping devices. The high force generated by the device is employed e.g. for stamping numbers and letters and other markings onto/into articles, generally articles comprised of metal. In particular, such stamping devices are used for stamping vehicle frame numbers or the like, in automotive manufacture.
DE 199 42 390 A1 discloses implements of the general type described in “Specific area” supra, employing a toggle-lever welding arm (welding arm driven by a toggle lever mechanism). Here a welding electrode is associated with the clamping arm, and the opposing electrode may be connected with the opposing jaw member opposed to the clamping arm. The metal sheets which are to be permanently joined are placed between the electrodes and are welded together by spot welding.
DE 36 13 644 A1 relates to a toggle-lever clamping device for holding of workpieces, particularly in automotive body manufacturing, having an axially adjustable member which actuates the toggle lever mechanism and which is associated with an electric drive which provides the axial movement. The electric drive drives a screw spindle or helical ball bearing screw spindle or the like, via an intermediate gear. The axially adjustable part may also be driven by an electrical linear motor.
U.S. Pat. No. 4,700,936 relates to a clamping device wherein an angle lever is driven by a worm drive. The worm drive is disposed outside the contours of the device head, which arrangement increases the apparatus size. For broaches, other mandrels, welding devices, and centering devices, employing toggle-lever clamping devices or toggle lever mechanisms, for the automotive industry (automotive body manufacture), this device cannot be used for this reason (non-compactness).
The underlying problem of the invention is to devise an implement of the general type described initially supra (“Specific area”), particularly for use in body manufacture in the automotive industry, which has a robust and structurally simple engineering design and substantially allows use of customary commercially available components.
In the inventive implement the drive part employs an ordinary commercially available electric motor, DC or AC or 3-phase or polyphase, 24 V or 220 V, which is attached directly to the head part by flange means, and the actuating member is driven by a transmission, which may be e.g. a worm drive. Electric motors of this type are employed with the selection of the motor depending on the desired power and performance.
A worm drive is robust and enables a large number of operating cycles (reciprocal excursions of the actuating member). Because only two drive elements are required for force transmission, viz. a worm gear wheel and a worm, the sealing problems which arise, e.g. when compressed air drive is employed, do not exist. Also it is unnecessary to run (have available) compressed air lines, because the motor is supplied with energy through an electric cable, which is convenient and compact. Further, the parts are relatively easy to disassemble for maintenance and repair. The electric motor can be separated from the head part quickly and easily, in order to replace said motor or perform maintenance on it. Worms and worm gear wheels can be readily accommodated inside the dimensions of the head part used as a clamping head in toggle-lever clamping devices or the like; thus it is unnecessary to increase the device dimensions. Thus implements having the inventive construction can be used anywhere toggle-lever clamping devices, toggle-lever welding arms, stamping tools, impressing tools, “clinch” tools, or clamping or broaching cylinders employing rods, have been used, e.g. for body manufacture in the automotive industry.
According to the invention the worm is rotatably mounted on the motor shaft which is drivable in two opposite directions by the electric motor. The worm gear wheel is disposed on a rotatably mounted shaft the position of which is fixed in the head part, which shaft can also be rotated in two directions. These shafts, and the worm gear wheel itself, may be disposed in antifriction bearings, which advantageously may be, e.g., needle bearings (to reduce apparatus dimensions).
Advantageously, the worm gear wheel is connected transmission-wise to the toggle lever mechanism and/or to members of the toggle lever mechanism, via a dog (21) and via a swing pivot (23). Because ordinarily the longitudinal axis of the worm and the longitudinal axis of the swing pivot of the worm gear wheel are disposed at a 90° angle (which is a skew angle), these drive parts are arranged compactly in the head part, e.g. in the clamping head of a toggle-lever clamping device.
The longitudinal axis of the swing pivot by which the relevant member of the toggle lever mechanism is connected to the dog member on the worm gear wheel is parallel to the longitudinal axis of the worm gear wheel.
Overall, the invention provides the advantage that the drive means can be accommodated in the clamping head, in space-saving fashion. At the same time, an ordinary commercially available electric motor may be used, and a robust worm drive. The worm and worm gear wheel can be housed inside the normal dimensions of the clamping head of, e.g., an implement in the form of a toggle-lever clamping device, without having to increase the dimensions of the device.
According to an illustrated embodiment, the worm shaft can be readily rotatably mounted in the head part, via two bearings spaced a distance apart, which bearings may comprise, e.g., antifriction bearings (needle bearings, ball bearings, or the like).
Illustratively, each of the levers connected to the dog member of the worm gear wheel is comprised of at least two lever members the longitudinal axes of which are at a mutual oblique angle, such that the apex of the angle is directed generally away from the longitudinal axis of the worm.
In this way one provides a large excursion path of the actuating member driven by the toggle lever mechanism; and the lever members of the toggle lever mechanism are accommodating toward the contour of the worm gear wheel so as not to interfere with it as they are driven by the electric motor, so that without increasing the transverse dimensions of customary clamping heads of toggle-lever clamping devices or the like it is possible to house all of these drive parts in the head part.
According to an illustrated embodiment part of the toggle lever mechanism is readily movably but forcibly guided via inner slot-shaped guide grooves which extend mutually parallelly in the longitudinal direction of the head part. These grooves are of identical shape.
According to an illustrated embodiment, the guiding is via rolls which have antifriction bearings, which bearings may advantageously be needle bearings in order to save space.
According to an illustrated embodiment, a shaft of the worm gear wheel (which shaft preferably has antifriction bearings) extends out of the head part without a loss of the sealing of the interior of the head part, such extension being on at least one side but preferably on both sides, wherewith the extended part of the shaft has a suitable coupling configuration to have a hand lever mounted on it. In this manner, if needed the implement can also be actuated manually, e.g. in the clamping position or in the open position.
According to an illustrated embodiment position sensing elements are disposed in the region of the toggle lever mechanism. These elements may be microswitches, inductive switches, or pneumatic switches, which are disposed on a replaceable module which is referred to in the industry as a “set” or “cassette”. These sensors may provide remote monitoring of, e.g., the clamping position of a clamping arm of a toggle-lever clamping device, the position of a centering mandrel, or the position of electrodes of toggle-lever welding devices or the like. These elements may enable connection of acoustic and/or optical indicating devices, e.g. in the form of light-emitting diodes, lamps, or the like, by electrical or electronic means, which devices provide remote monitoring of the position of a given actuating member, wherewith the monitoring appears e.g. at a remote control post where a number of implements are monitored, particularly toggle-lever clamping devices in factories for automobile bodies in the automotive industry
According to an illustrated embodiment, advantageously the described replaceable module can be inserted/accommodated in the head part from all four sides.
The longitudinal slots therefore which are not needed (not in use) are closed off by suitable means, e.g. sheet metal pieces.
According to an illustrated embodiment, attachment means in the form of threaded blind holes, quick connections, throughgoing bores, or the like may be provided on all four sides (front, rear, and lateral) of the head piece, facilitating the positioning of the module which is insertable in the longitudinally extending narrow slot in the head part. Also, e.g., threaded blind holes may be provided on both sides of the slot, in order to facilitate positioning of the overall apparatus, e.g. for integrating the apparatus into the body assembly line of an automobile factory. Numerous opportunities for so integrating the inventive implement are thus provided.
According to an illustrated embodiment, the transmission means is self-locking.
According to an illustrated embodiment, the implement has a battery for emergency power supply purposes, which battery may be associated with the drive part and may be automatically charged/recharged by operation of the motor, wherewith when there is a power failure the battery automatically provides electricity for operating the implement.
According to an illustrated embodiment, the worm and/or the worm gear wheel is/are comprised of materials which have operating characteristics which enable continued operation under emergency conditions. For example, the worm and/or the worm gear wheel may be comprised of a suitable plastic material a component of which is flakes (or the like) of polytetrafluoroethylene (PTFE). E.g. the worm and/or worm gear wheel may be formed by casting or injection molding, and they may have contours formed (by machining or the like) into their surfaces such that pieces of such PTFE bodies (flakes or the like) become prominent or exposed, whereby the interengaging surface areas of the worm and worm gear wheel can operate for an extended period without lubrication.